Backyard Aquaponics

Did I kill my fish with kelp overdose ?
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Author:  maxhill [ Jun 17th, '16, 18:44 ]
Post subject:  Did I kill my fish with kelp overdose ?


My system was running smoothly with reasonable parameters for the last few months

2000+ litres
70 plants in big growbed , 6 small grow towers and a couple of mint rafts straight in the fish tank.
fish 30 goldfish

My last tests a few days before the incident were:
ph 7.4
ammonia zero
nitrites zero
nitrates 60 ppm
salinity 3ppm

I have two airstones with appropriately sized airpump

I decided to start supplementing with calcium and potassium for my tomato plants' fruiting stage

I bought a kg of kelp powder of ebay.

I added 3 ounces to 1 gallon of water and started pouring in grow bed. Then I thought, couldn't hurt to add a bit of powder straight in the grow bed drain, to get it cycling. Then for some reason, I tried adding another 3 ounces straight into the fish pond. So about 9 ounces in total, some disolved in water , some straight powder.

I thought , it couldn't hurt right. It's just kelp. The next day I lost 15 fish.

I'm assuming it's the kelp since I hadn't done anything else out of the ordinary other than supplement with FeEDDHA a few days earlier.

I've seen at least two other posts online of similar stories with people doing to much kelp at a time.

What exactly is it about the kelp that killed them though? Is there some sort of toxicity? Too much potassium or other component? Or is it mechanical i.e. blocking gills , oxygen depleting?

I did notice one thing and that is that the fish were going for the powder and may have eaten some. I also noticed that the powder I sprinkled in the grow bed swelled up when wet into a paste. Could they have eaten and then caused issues inside them?

Anyone think it couldn't possibly be the kelp maybe and should I be looking at other things before replacing the fish?

Also strangely , when I did the nitrate test after I discovered and removed the fish, all the nitrates (60ppm) where gone and I couldn't detect any. I found that peculiar. There were 5 days between last test and kellp incident and another day between discovering the dead fish and redoing a test. Can it go from 60 ppm to 0ppm , so quickly?

Author:  scotty435 [ Jun 17th, '16, 23:52 ]
Post subject:  Re: Did I kill my fish with kelp overdose ?

Sorry to hear about your fish. I can't tell you what component/s killed the fish but it makes sense that this was the cause. Since you were supplying growth promoters to the plants (in the kelp) but even if you hadn't been, it's entirely possible that all the nitrates disappeared in only 5 days.

Author:  PhillipAquaponics [ Jun 30th, '19, 02:30 ]
Post subject:  Re: Did I kill my fish with kelp overdose ?

I just experienced the same thing in my home system and after some research I can only conclude we poisoned our fish with Iodine. Kelp powder is rich in iodine and in high concentrations can become toxic. It's the only rational explanation I could come up with as none of the kelp powder I used was added directly to the fish tank. It was thinned out with water and strained through a mesh strainer, so there were no large particles. It was added to my sump pump tank and so it was further diluted before it hit the fish tank. It just had to be the amount I used because when I used it before I had no problems but when previously added to the sump pump, I added it dry and so it was clumpy and I think it acted almost as a slow release. Such a small thing yet I lost one fish hopefully that is all. Hope this helps.

Author:  Mr Damage [ Jul 2nd, '19, 10:27 ]
Post subject:  Re: Did I kill my fish with kelp overdose ?

Did you test the Ammonia level a few hours after adding the kelp?... It contains Ammonia, that's why people use seaweed extract to cycle new systems. With your pH in the mid 7's and warm weather it wouldn't have taken much to be toxic to your fish.

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